Final answer:
In the debates with Douglas, Lincoln maintained that slavery was morally wrong and warned against its potential 'nationalization'. He disagreed with its further expansion and held Douglas accountable to explain his stance on the Dred Scott case. These debates helped elevate Lincoln's national profile.
Step-by-step explanation:
During the debates between Abraham Lincoln and Stephen Douglas, the key issue they delved into was slavery and its expansion. Lincoln's stance on slavery was complex. He morally opposed slavery and believed it was inherently wrong. He didn’t support its expansion and propagated the message that a nation divided on the issue of slavery would not stand. However, he did accept the contemporaneous racism present in the society. He warned that Douglas and the Democrats could possibly subvert the intention of popular sovereignty to 'nationalize' slavery.
On the question of the 1857 Dred Scott case, Lincoln needed Douglas to explain whether he believed the Supreme Court's decision overrode the majority's right to halt the spread of slavery. Douglas, in his Freeport Doctrine, supported popular sovereignty, stating that the public had the lawful means to either introduce or exclude slavery irrespective of the Supreme Court's decision. Although Douglas won the election, the debates elevated Lincoln's national profile.
Learn more about Lincoln-Douglas debates